The present invention broadly relates to the papermaking art, and, in particular, is directed to a new and improved construction of a headbox for a papermaking machine.
Generally speaking, the headbox of the present development for a papermaking machine is of the type comprising a guide block possessing at least one guide channel through which flows the fiber stock suspension. A nozzle chamber merges with the guide block and is bounded by two lips or lip members which form a slice opening or outlet slice for the efflux of the fiber stock suspension. The nozzle chamber is subdivided into at least two nozzle chambers or sub-passageways by at least one adjustable partition or divider wall.
Such type of headbox is disclosed, for instance, in the German Patent No. 3,227,218 or the U.S. Pat. No. 4,543,162, granted Sept. 24, 1985. This headbox serves for the fabrication of a multi-ply paper web by mutually independently charging or infeeding the individual nozzle chambers with fiber stock suspensions. The partition walls between the individual nozzle chambers are designed to be displaceable in the direction of flow of the fiber stock suspensions in order to be able to regulate or adjust different velocities and pressures of the fiber stock suspension in the individual nozzle chambers. As a result, it is possible to regulate and adjust to a certain degree, the properties of the individual plys of the produced paper web but the adjustment possibilities are not totally adequate for certain multi-ply types of paper.
It is also already known to construct the partition walls in the nozzle chamber to be flexible, so that they automatically adjust themselves in a manner such that in all of the nozzle chambers, there prevails the same pressure. With this headbox design, it is not possible to adjust the flow of the fiber stock suspension in the individual nozzle chambers and it is also not possible to adjust independently of one another, the outlet slices or slice openings of the individual paper plys.